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stephen_usher
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Re: General Stuff(tm)

Post by stephen_usher »

I'm getting really fed up with this hot weather. Not only is it hard to sleep but it's too warm to do much upstairs on the machines.

Then again, with the lack of sleep I'm not sure I could hold a soldering iron the right way around at the moment.
Intro retro computers since before they were retro...
ZX81->Spectrum->Memotech MTX->Sinclair QL->520STM->BBC Micro->TT030->PCs & Sun Workstations.
Added code to the MiNT kernel (still there the last time I checked) + put together MiNTOS.
Collection now with added Macs, Amigas, Suns and Acorns.
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rubber_jonnie
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Re: General Stuff(tm)

Post by rubber_jonnie »

stephen_usher wrote: Fri Aug 12, 2022 9:16 am I'm not sure I could hold a soldering iron the right way around at the moment.
Hey, that's my job...

:dizzy:
Collector of many retro things!
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
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stephen_usher
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Re: General Stuff(tm)

Post by stephen_usher »

rubber_jonnie wrote: Fri Aug 12, 2022 9:23 am
stephen_usher wrote: Fri Aug 12, 2022 9:16 am I'm not sure I could hold a soldering iron the right way around at the moment.
Hey, that's my job...

:dizzy:
:lol: :excited:
Intro retro computers since before they were retro...
ZX81->Spectrum->Memotech MTX->Sinclair QL->520STM->BBC Micro->TT030->PCs & Sun Workstations.
Added code to the MiNT kernel (still there the last time I checked) + put together MiNTOS.
Collection now with added Macs, Amigas, Suns and Acorns.
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stephen_usher
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Joined: Mon Nov 13, 2017 7:19 pm
Location: Oxford, UK.
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Re: General Stuff(tm)

Post by stephen_usher »

Now that the temperature has dropped I can get back to stuff.

I packed away the Falcon and worked upon the serial I/O board of a musical keyboard. The board had a leaky VARTA, which was removed, but the juice had tarnished the legs on the ROM and SRAM chips. Thankfully it hadn't done much real damage.

After cleaning the legs of the chips with a fibreglass pencil and the sockets with electrolube + a wooden cocktail stick to polish the contacts the board came back to life, or at least it looks as though it is, as I only have the board and not the whole keyboard. The outputs looked to be doing sensible things and the address bus wasn't constantly repeating the same addresses. It looked as if it was doing sensible things.

I then turned my attention to the battery area and looked at installing a CR2032 socket. At first I thought that I would have to put the socket on some vero-board with a diode but then noticed that two of the vias were in precisely the correct location for the leads in the socket. Clearing one wasn't a problem but the other was difficult due to battery juice corrosion, so I had to carefully drill that one out.

Anyway, the socket fitted nicely. I then lifted one end of the 1K resistor between the battery and the system and installed a diode to prevent power getting back to the lithium cell. All done and tidy...

IMG_2770.jpg
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Intro retro computers since before they were retro...
ZX81->Spectrum->Memotech MTX->Sinclair QL->520STM->BBC Micro->TT030->PCs & Sun Workstations.
Added code to the MiNT kernel (still there the last time I checked) + put together MiNTOS.
Collection now with added Macs, Amigas, Suns and Acorns.
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stephen_usher
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Location: Oxford, UK.
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Re: General Stuff(tm)

Post by stephen_usher »

No computery things today, just starting upon getting an old Hornby loco working again.

Back in the mid-80s I stripped out the gears, commutator etc. from the ringfield motor as the bearings had worn out and the loco became a static item on the layout.

Having just bought a CD motor conversion kit and a set of gears I've been starting to get it operational again.

The motor bogie is now working but I'm having to wait for the special connectors to allow the wires to connect to the motor frame and the undriven bogie to get power. The weight has gone missing as well so I'm getting a replacement for that too. By the end of the week the loco should be operational again nearly 40 years after it last ran.

IMG_2771.jpg
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Intro retro computers since before they were retro...
ZX81->Spectrum->Memotech MTX->Sinclair QL->520STM->BBC Micro->TT030->PCs & Sun Workstations.
Added code to the MiNT kernel (still there the last time I checked) + put together MiNTOS.
Collection now with added Macs, Amigas, Suns and Acorns.
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stephen_usher
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Joined: Mon Nov 13, 2017 7:19 pm
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Re: General Stuff(tm)

Post by stephen_usher »

And now the Hymek is fully wired up and able to move under its own power for the first time since about 1983.

IMG_2772.jpg
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Intro retro computers since before they were retro...
ZX81->Spectrum->Memotech MTX->Sinclair QL->520STM->BBC Micro->TT030->PCs & Sun Workstations.
Added code to the MiNT kernel (still there the last time I checked) + put together MiNTOS.
Collection now with added Macs, Amigas, Suns and Acorns.
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stephen_usher
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Joined: Mon Nov 13, 2017 7:19 pm
Location: Oxford, UK.
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Re: General Stuff(tm)

Post by stephen_usher »

All the model railway stuff packed away again and with a month to go until the show in Hyde it's time to start planning and prepping machines.

So, the MTX512 is back from storage so I can see if I can get the keyboard switches to work reliably and not generate multiple key strokes every time they're pressed. They're the same key switches as used in some BBC Micros, which suffer the same issue if the machine has been stored in a damp environment at some time. The switches rely upon a thin brass leaf to be pressed against two chromed columns by a plunger. Unfortunately the contact area is only at the end of the plunger, so as it descends different parts of the leaf and columns make contact. Any corrosion will prevent the switch actuating once as the contacts will make and break connection as the plunger moves. This will happen both for the descending and rising motion and differ depending upon the angle at which the plunger is being pressed by the person's finger. It's quite a poor design.

Anyway, I've got a key cap puller on order so i don't have to dismantle the top of the case. Some of the nuts are very hard to get to as they're under the actual keyboard PCB. I wish Memotech had put cut-outs in the PCB for access. It would have made their assembly process far quicker and simpler.

Once I have the puller I can try squirting Electrolube down the key posts and actuate them many times. I did try this previously but the contact cleaner was one of the types which didn't have a reducing agent chemical in the mix so it didn't work.
Intro retro computers since before they were retro...
ZX81->Spectrum->Memotech MTX->Sinclair QL->520STM->BBC Micro->TT030->PCs & Sun Workstations.
Added code to the MiNT kernel (still there the last time I checked) + put together MiNTOS.
Collection now with added Macs, Amigas, Suns and Acorns.
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stephen_usher
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Joined: Mon Nov 13, 2017 7:19 pm
Location: Oxford, UK.
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Re: General Stuff(tm)

Post by stephen_usher »

I've not got the key cap puller yet so all I can do is mash keys at the moment.

I've got a few more keys working better...

IMG_2773.jpg
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Intro retro computers since before they were retro...
ZX81->Spectrum->Memotech MTX->Sinclair QL->520STM->BBC Micro->TT030->PCs & Sun Workstations.
Added code to the MiNT kernel (still there the last time I checked) + put together MiNTOS.
Collection now with added Macs, Amigas, Suns and Acorns.
User avatar
stephen_usher
Posts: 5580
Joined: Mon Nov 13, 2017 7:19 pm
Location: Oxford, UK.
Contact:

Re: General Stuff(tm)

Post by stephen_usher »

Ouch... My fingers hurt from hammering keys to try to get them to work now.
Intro retro computers since before they were retro...
ZX81->Spectrum->Memotech MTX->Sinclair QL->520STM->BBC Micro->TT030->PCs & Sun Workstations.
Added code to the MiNT kernel (still there the last time I checked) + put together MiNTOS.
Collection now with added Macs, Amigas, Suns and Acorns.
User avatar
mrbombermillzy
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Joined: Sun Jun 03, 2018 7:37 pm

Re: General Stuff(tm)

Post by mrbombermillzy »

That's an interesting little machine there. I hope you get the keys working in time for the show.

I only really noticed the Memotech brand when I was at a Vintage car show a few weeks ago:

viewtopic.php?p=89246#p89246

Glad to hear you are prepping in good time. :D

I suppose that I should start doing that soon. For me, it's more of an issue finding the leads for various bits and bobs.

For example, I seem to have misplaced my mono mini jack lead for the 128k toastrack to tape deck and cannot find a C64 floppy data lead either for the 1541Pi. Also, it's a shame I probably won't have time to make up a cable for the Aydin Ranger RGB Multisync monitor...I may bring it anyway, as its got RGBI too, which is good for the C128D VDC 80 column mode.
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